Not exactly a Linux tip, but it's one that I usually use to see where spammers are getting my email address from...

If you own your own domain with email, most will give you unlimited forwarding email addresses that will forward to your mail webmaster / admin / user email address. When I sign up for a forum / online anything I use the email address

Then if I get any spam emails I can work out where the spammers got the email address from - plus you can cancel the forwarding there-and-then.

So if it was for this site and it was me I would use If I then got any spam emails I would know that the spammers got the address from this site or the webmaster had sold the addresses to them.